»/*!  CIS,     JO     C/SA'TS. 


THE 


PROBLEM  OF  MANFLIGHT 


BY 


JAMES     M  E  ANS 


V*2fef 


THE     FLIGHT    OF    OTTO     LILIENTHAL,     OF     STEGL1TZ,     PRUSSIA,    AS    ACTUALLY 

ACCOMPLISHED     IN     1893.      ACCURATELY    DRAWN     FROM 

AN    INSTANTANEOUS    PHOTOGRAPH. 


BOSTON,     MASS.  : 

W.     B.     CLARK  E     &     CO., 

340   WASHINGTON   STREET. 

1894. 


THE    PROBLEM 


MANFLIGHT. 


BY 


JAMES    MEANS, 


This  pamphlet  will  be  sent,  postpaid,  to  any 
address   on   receipt  of  ten    cents  in    stamps. 


BOSTON,    MASS. : 
W.     B.     CLARKE     &     CO., 

340    WASHINGTON    ST. 
1894. 


>•?»"%• 


Copyright,  1894, 
*  Jf  V "  J  A  M  E<S .'  &  fi  it  if  S. 


»0rftJ»ell  antj 

BOSTON 


•    - 

' 


THE    PROBLEM     OF     MANFLIGHT, 


As  the  century  draws  to  its  close  the  interest  in  the 
subject  of  aeronautics  steadily  increases.  There  already 
exists  a  keen  curiosity  to  know  what  the  aerial  machine 
of  the  future  is  likely  to  resemble,  and  also  to  know 
whether  the  nineteenth  or  the  twentieth  century  will 
claim  it  for  its  own. 

In  the  present  article  the  writer  wishes  to  show  what 
inferences  may  be  drawn  from  the  laws  of  nature  as  so 
far  ascertained  by  observation  and  experiment,  and  he 
wishes  also  to  point  out  a  way  which  may  lead  to 
further  progress. 

The  investigators  of  this  subject  are  now  divided  into 
two  camps  :  on  the  one  side  there  are  men  who,  like 
Mr.  Maxim,  are  endeavoring  to  construct  machines 
which  will  carry  motors  and  therefore  be  self-propel- 
ling ;  on  the  other  side  there  are  men  like  Mr.  A.  M. 
Wellington,  who  maintains  that  a  motor  is  unnecessary 
and  that  wind-power  is  sufficient. 

In  the  New  York  Engineering  News,  of  Oct.  12^ 
1893,  Mr.  Wellington,  in  a  very  interesting  article  en- 
titled w  The  Mechanics  of  Flight,"  makes  the  following 
statement  :  "If  the  conclusions  so  far  reached  in  this 
paper  be  accepted,  it  is  obvious  that  they  greatly 
simplify  the  problem  of  artificial  flight  by  reducing  to  a 
minimum  the  demand  for  power,  making  it  chiefly 
necessary  for  acquiring  the  first  initial  velocity.  All 
attempts  at  aviation  which  include  any  motor  for  pro- 

M46810 


4  THE    PROBLEM    OF    MANFLIGHT. 

pulsion  are,  in  my  judgment,  on  wrong  lines,  and  pre- 
destined to  certain  failure,  since  they  not  only  neglect, 
but  destroy,  the  action  of  the  forces  by  which  true  flight 
may  be  and  is  attained.  I  will  not  go  so  far  as  to  say 
that  some  (soaring)  birds,  in  the  exuberance  of  power, 
may  not  use  the  wings  to  accelerate,  as  they  do  to  retard 
motion.  I  think  they  do,  but  only  in  an  abnormal  way  ; 
it  is  wholly  unnecessary,  and  even  destructive  of  all 
normal  flight.  The  fish  needs  a  propeller,  because  it 
has  no  gravity  in  water;  the  bird  does  not  need  it, 
because  it  has  gravity,  and  in  that  gravity  has  the  best 
and  smoothest  of  all  conceivable  means  of  propulsion,  if 
he  can  make  the  wind  lift  him  uphill  whenever  he  has 
slid  far  enough  downhill.  If  so,  man  commits  an  ab- 
surdity when  he  flies  in  the  face  of  nature  and  assumes 
a  propelling  force  where  none  is  needed  or  exists." 

Later  on  in  this  article,  I  wish  to  describe  an  instru- 
ment, experiments  with  which  can  be  made  to  answer 
for  us  the  question  as  to  whether  or  not  a  motor  is 
needed;  but  just  here  further  quotations  should  be  given 
to  show  the  trend  of  the  best  thought. 

Aeronautics  (N.Y.)  for  January  contains  Professor 
Langley's  remarkable  paper  entitled  ':c  The  Internal 
Work  of  the  Wind."  The  closing  paragraph  is  as 
follows : 

w  The  final  application  of  these  principles  to  the  art 
of  aerodromics  seems,  then,  to  be,  that  while  it  is  not 
likely  that  the  perfected  aerodrome  (air-runner)  will 
ever  be  able  to  dispense  altogether  with  the  ability  to 
rely  at  intervals  on  some  internal  source  of  power,  it 
will  not  be  indispensable  that  this  aerodrome  of  the 
future  shall,  in  order  to  go  any  distance  —  even  to  cir- 
cumnavigate the  globe  without  alighting,  —  need  to  carry 
a  weight  of  fuel  which  would  enable  it  to  perform  this 


THE    PROBLEM    OF    MANFLIGHT.  5 

journey  under  conditions  analogous  to  those  of  a  steam- 
ship, but  that  the  fuel  and  weight  need  only  be  such  as 
to  enable  it  to  take  care  of  itself  in  exceptional  moments 
of  calm." 

Mr.  Octave  Chanute,  in  his  admirable  chronicle  en- 
titled "  Progress  in  Flying-Machines,"  which  will  soon 
be  published,  says  in  one  of  his  closing  chapters:  w  But 
it  is  possible  to  utilize  a  still  lighter  power  [than  that 
of  engines],  for  we  have  seen  that  the  wind  may  be 
availed  of  under  favorable  circumstances,  and  that  it 
will  furnish  an  extraneous  motor  which  costs  nothing 
and  imposes  no  weight  upon  the  apparatus. 

:<r  Just  how  much  power  can  be  thus  utilized  cannot 
well  be  told  in  advance  of  experiment;  but  we  have 
calculated  that  under  certain  supposed  conditions  it 
may  be  as  much  as  some  six-horse  power  for  an  aero- 
plane with  one  thousand  square  feet  of  sustaining 
surface ;  and  we  have  also  seen  that  while  but  few  ex- 
perimenters have  resorted  to  the  wind  as  a  motor,  those 
few  have  accomplished  remarkable  results." 

The  indications  seem  to  be  that  we  must  try  to  con- 
struct a  machine  analogous  to  the  sailing-yacht  rather 
than  to  the  steamship,  though  perhaps  the  aerial  machine 
of  the  future  will  be,  so  far  as  power  is  concerned, 
analogous  to  the  yacht  Sunbeam  with  its  auxiliary 
screw. 

Before  continuing  further  with  this  subject,  I  wish  to 
call  attention  to  certain  facts  concerning  the  storage  of 
power  and  the  flight  of  soaring  birds.  First,  in  regard 
to  the  storage  of  power.  It  is  well  known  that  the  con- 
struction of  a  useful  electric  storage-battery  presents  a 
most  difficult  problem.  Such  a  storage  device  is  needed 
for  use  upon  the  surface  of  the  earth;  yet,  for  purposes 
of  aerial  navigation,  there  is  a  much  simpler  accumulator 


6  THE    PROBLEM    OF    MANFLIGHT. 

which  can  be  used.  Take,  for  example,  one  hundred 
pounds  of  lead  and  let  energy  be  stored  in  it  by  giving 
it  altitude,  just  as  energy  is  stored  in  the  weight  of  a 
clock  when  it  is  wound. 

What  is  known  as  one-horse  power  is  the  amount  of 
energy  which  must  be  exerted  in  lifting  thirty-three 
thousand  pounds  at  the  rate  of  one  foot  per  minute,  or 
five  hundred  and  fifty  pounds  at  the  rate  of  one  foot  per 
second,  or  fifty-five  pounds  at  the  rate  of  ten  feet  per 
second.  To  give  an  illustration,  it  may  be  stated  that  if 
a  man  weighing  one  hundred  and  sixty-five  pounds 
ascends  a  flight  of  steps  ten  feet  high  in  three  seconds, 
he  exerts  for  the  time  being  just  one  standard  horse- 
power. 

A  small  balloon  which  can  lift  one  hundred  pounds 
of  lead  three  hundred  and  thirty  feet  high  in  one  minute 
exerts  one-horse  power. 

The  lead  when  lifted  to  this  height  has  stored  within 
itself  thirty-three  thousand  foot-pounds  of  energy. 

Now,  if  weights  can  be  made  to  slide  downhill  upon 
aeroplanes  at  very  gentle  grades,  then  the  balloon  be- 
comes a  valuable  motor  which  stores  energy  in  its  load 
by  giving  it  altitude,  and  the  weight  lifted  becomes  a 
reservoir  of  the  very  power  needed  for  its  own  trans- 
portation, and  the  name  of  Montgolfier,  the  inventor  of 
the  under-estimated  balloon,  takes  its  place  as  that  of  the 
real  founder  of  the  useful  art  of  aerial  transportation. 

Whether  or  not  it  is  possible  to  transport  freight  by 
sliding  it  down  long  and  gentle  inclines  by  means  of 
aeroplanes  will  be  considered  further  on;  just  here  we 
must  consider  the  soaring  power  of  birds. 

In  w  The  Reign  of  Law,"  by  the  Duke  of  Argyll  (first 
published  in  1867),  there  is  a  most  notable  chapter  in 
which  the  flight  of  birds  is  analyzed.  In  a  note  the 


THE    PROBLEM    OF    MANFLIGHT.  7 

author  makes  the  following  statement:  w  I  owe  to  my 
father  [John,  seventh  Duke  of  Argyll]  my  knowledge  of 
the  theory  of  flight,  which  is  expounded  in  this  chapter. 
The  retired  life  he  led,  and  the  dislike  he  had  of  the 
work  of  literary  composition,  confined  the  knowledge 
of  his  views  within  a  comparatively  narrow  circle.  But 
his  love  of  mechanical  science,  and  his  study  of  the 
problem  during  many  years  of  investigation  and  experi- 
ment, made  him  thoroughly  master  of  the  subject." 

Every  student  of  the  subject  of  flight  should  read  the 
interesting  work  just  mentioned.  We  may  not  agree 
with  all  the  conclusions  which  are  reached,  yet  the 
author  gives  most  stimulating  food  for  thought. 

The  following  paragraphs  are  among  the  most  strik- 
ing, showing,  as  they  do,  advanced  ideas: 

w  In  the  first  place,  it  is  remarkable  that  the  force 
which  seems  so  adverse  —  the  force  of  gravitation 
drawing  down  all  bodies  to  the  earth — is  the  very  force 
which  is  the  principal  one  concerned  in  flight,  and  with- 
out which  flight  would  be  impossible.  It  is  curious  how 
completely  this  has  been  forgotten  in  almost  all  human 
attempts  to  navigate  the  air.  Birds  are  not  lighter  than 
the  air,  but  immensely  heavier.  If  they  were  lighter 
than  the  air  they  might  float,  but  they  could  not  fly» 
This  is  the  difference  between  a  bird  and  a  balloon."  (p. 
130,  Am.  ed.) 

"  No  bird  is  ever  for  an  instant  of  time  lighter  than 
the  air  in  which  it  flies  ;  but  being,  on  the  contrary, 
always  greatly  heavier,  it  keeps  possession  of  a  force 
capable  of  supplying  momentum,  and  therefore  capable 
of  overcoming  any  lesser  force,  such  as  the  ordinary 
resistance  of  the  atmosphere,  and  even  heavy  gales  of 
wind.  The  force  of  gravitation,  therefore,  is  used  in 


8  THE    PROBLEM    OF    MANFLIGHT. 

the  flight  of  birds  as  one  of  the  most  essential  of  the 
forces  which  are  available  for  the  accomplishment  of  the 
end  in  view."  (p.  131.) 

"  The  lightness  of  a  bird  is  a  limit  to  its  velocity. 
The  heavier  a  bird  is,  the  greater  is  its  possible  velocity 
of  flight  —  because  the  greater  is  the  store  of  force  ; 
or,  to  use  the  language  of  modern  physics,  the  greater  is 
the  quantity  of  '  potential  energy '  which,  with  proper 
implements  to  act  upon  aerial  resistance,  it  can  always 
convert  into  upward,  or  horizontal,  or  downward  motion, 
according  to  its  own  management  and  desires."  (p. 
144.) 

"  When  a  strong  current  of  air  strikes  against  the 
wings  of  a  bird,  the  same  sustaining  effect  is  produced 
as  when  the  wing  strikes  against  the  air.  Consequently 
birds  with  very  long  wings  have  this  great  advantage, 
that,  with  pre-acquired  momentum,  they  can  often  for 
a  long  time  fly  without  flapping  their  wings  at  all. 
Under  these  circumstances  a  bird  is  sustained  very 
much  as  a  boy's  kite  is  sustained  in  the  air.  The  string 
which  the  boy  holds,  and  by  which  he  pulls  the  kite 
downwards  with  a  certain  force,  performs  for  the  kite 
the  same  offices  which  its  own  weight  and  balance  and 
momentum  perform  for  the  bird.  The  great  long- 
winged  oceanic  birds  often  appear  to  float  rather  than 
to  fly.  The  stronger  is  the  gale,  their  flight,  though  less 
rapid,  is  all  the  more  easy,  so  easy  indeed  as  to  appear 
buoyant ;  because  the  blasts  which  strike  against  their 
wings  are  enough  to  sustain  the  bird  with  comparatively 
little  exertion  of  its  own,  except  that  of  holding  the 
wing  vanes  stretched  and  exposed  at  proper  angles  to 
the  wind.  And  whenever  the  onward  force  previously 


THE    PROBLEM    OF    MANFLIGHT.  9 

acquired  by  flapping  becomes  at  length  exhausted,  and 
the  ceaseless,  inexorable  force  of  gravity  is  beginning 
to  overcome  it,  the  bird  again  rises  by  a  few  easy  and 
gentle  half-strokes  of  the  wing.  Very  often  the  same 
effect  is  produced  by  allowing  the  force  of  gravity  to 
act,  and  when  the  downward  momentum  has  brought 
the  bird  close  to  the  ground  or  to  the  sea,  that  force  is 
.again  converted  into  an  ascending  impetus  by  a  change 
in  the  angle  at  which  the  wing  is  exposed  to  the  wind." 
(p.  152.) 

It  is  to  be  regretted  that  the  limits  of  this  article  pre- 
vent more  extended  quotations  from  this  remarkable 
book. 

Now  let  us  recall  what  we  have  seen  at  sea. 

When  one  stands  on  the  after-deck  of  a  steamer  in 
crossing  the  ocean,  he  may  watch  the  soaring  gulls  to 
his  heart's  content.  When  the  ship  struggles  painfully 
to  force  her  way  into  the  teeth  of  a  gale,  the  birds  make 
sport  for  themselves  —  they  rise  and  dip,  thus  conquering 
the  wind.  How?  Simply  by  tacking;  in  one  sense, 
just  as  a  yacht  tacks  to  windward.  Neither  bird  nor 
yacht  can  sail  into  the  eye  of  the  wind  by  the  wind's 
power,  but  either  can,  by  use  of  that  power,  reach  an 
•objective  point  lying  to  windward. 

But  here  the  reader  may  say  that  the  parallelism  be- 
tween the  bird  and  the  sailing  craft  is  not "  correctly 
drawn,  because  the  yacht  has  a  keel  immersed  in  a 
dense  medium  which  resists  and  prevents  the  making 
•of  leeway. 

Yet  the  soaring  bird  has  something  which,  at  neces- 
sary times,  holds  it  against  the  wind  just  as  effectually 
as  the  keel  holds  the  yacht:  that  something  is  momen- 
tum, which,  while  it  lasts,  holds  the  bird  against  the 
wind  as  firmly  as  the  kite-string  holds  the  boy's  kite. 


10 


THE    PROBLEM    OF    MANFLIGHT. 


In    Fig.   i,  let  S  represent  a  steamship  going    east- 
ward   at   the    rate  of  twenty  miles    per  hour;    W  the 


wind  blowing  westward  at  the  rate  of  twenty  miles  per 
hour;  A  a  gull  near  the  water's  surface,  with  mo- 
mentum which  for  the  instant  gives  him  an  eastward 
velocity  of  twenty  miles  per  hour.  While  the  bird's 
momentum  lasts  it  holds  him  firmly  against  the  wind. 
At  the  point  A  the  bird  inclines  his  wings  so  that  the 
wind  strikes  them  on  the  under  side,  and  he  is  lifted  and 
lifted  until,  at  the  point  B,  his  momentum  is  so  reduced 
that  he  must  tack;  then  he  gives  to  the  wind  the  thin 
edge  of  his  wings  and  slides  down  to  the  point  C,  and 
then,  with  velocity  regained,  he  repeats  the  manoeuvre. 
Altitude  sacrificed  becomes  velocity  or  momentum,  and 
momentum  sacrificed  becomes  altitude.  In  this  de- 
scription of  the  gull's  soaring  to  windward,  the  move- 
ment is  reduced  to  its  simplest  elements,  and  it  leaves 
out  of  account  the  graceful  sinuosity  of  the  bird's  airy 
travels,  just  as  the  teacher  of  dancing  leaves  grace  out 
of  account  when  she  teaches  the  beginner  the  elements 
of  the  steps. 

What  has  here  been  said  about  the  storage  of  energy 
in  weights,  and  concerning  the  elements  of  flight,  is  all 
intended  to  lead  up  to  the  important  subject  of  sliding 


THE    PROBLEM    OF    MANFLIGHT. 


II 


freight  downhill  upon  aeroplanes.       It  may   be  asked, 
How  about  a  calm? 

There  is  no  calm  for  the  aeroplane.    Give  it  altitude 
and  it  can  gain  velocity,  and  velocity  gives  the  'wind 

°f  flight- 

The  plan  for  the  transportation  of  freight  is  simply 

this:  at  each  shipping-point  a  power-house   (D,  Fig.  2) 


f»£ff    HOUR 


Fig.  2. 

may  be  established  to  operate  captive  balloons.  These 
should  be  cellular,  and  should  be  made  to  hold  gas 
with  little  waste.  In  its  action  the  apparatus  would  be 
what  might  be  called  an  inverted  elevator;  that  is,  the 
steam  or  water-motor  in  the  power-house  would  not 
hoist  the  freight,  but,  instead,  would  pull  the  balloon 
down  after  it  had  hoisted  the  freight  and  discharged 
it  by  means  of  a  soaring  machine,  which  will  presently 
be  described. 


12  THE    PROBLEM    OF    MANFLIGHT. 

In  Fig.  2  A  represents  a  captive  balloon  at  a  height 
of  one  thousand  feet.  B  and  C  represent  the  courses 
which  would  be  taken  by  dirigible  aeroplanes  or  soar- 
ing machines  bearing  loads  of  freight. 

Perhaps  this  seems  fanciful.  Then  let  it  be  remem- 
bered that  the  feat  of  safely  sliding  down  a  long  and 
gentle  incline  upon  an  aeroplane  has  already  been  per- 
formed by  Otto  Lilienthal,  of  Steglitz,  Prussia.  His 
experiments  were  illustrated  and  described  in  the  Berlin 
Illustrirte  Zeitung  of  Oct.  7,  1893,  and  one  of  the  draw- 
ings—  all  of  which  were  correctly  made  from  instan- 
taneous photographs  —  is  here  reproduced  on  the  first 
page  of  cover.  An  improvement  upon  Lilienthal's 
device  may  be  made  by  adding  a  pendulum.  * 

Now,  in  order  to  travel  long"  distances  in  the  air 
it  is  only  necessary  to  improve  the  dirigibility  of  the 
aeroplane  so  that  the  angle  of  descent  can  be  brought 
to  a  minimum. 

How  can  this  be  done?  By  making  repeated  ex- 
periments with  very  simple  and  inexpensive  mechan- 
ical contrivances  called  soaring  machines,  these  to  be 
dropped  from  a  height. 

In  Fig.  2  it  will  be  noticed  that  the  course  marked  B 
indicates  a  speed  of  twenty-five  miles  per  hour,  that 
marked  C  a  speed  of  one  hundred  miles  per  hour. 

What  speed  may  we  expect  of  an  improved  soaring- 
machine?  and  upon  how  gentle  a  decline  can  we  hope 
to  see  it  maintain  its  initial  velocity?  First,  note  the 
fact  that  with  a  dirigible  aeroplane  or  soaring  machine 
the  rate  of  speed  is  practically  a  matter  of  choice  and 
depends  at  the  start  upon  the  length  of  the  first  swoop. 
The  limit  of  speed  will  probably  be  decided  by  the 

*  See  U.  S.  Letters  Pat.  No.  376937. 


THE    PROBLEM    OF    MANFLIGHT.  13 

strength  of  the  machine  and  the  breathing  requirements 
of  the  aerial  pilot.  Let  us  consider  a  railroad  train. 
Man  has  safely  travelled  at  a  rate  of  one  hundred  and 
twelve  miles  per  hour.  On  May  n,  1893,  the  Empire 
State  express  on  the  N.Y.C.  R.R.  reached  that  speed 
in  a  mile  run  in  thirty-two  seconds,  one  mile  westward 
from  Crittenden.  So  we  know  that  man  can  safely 
breathe  when  travelling  at  over  one  hundred  miles  per 
hour;  yet  for  this,  of  course,  he  needs  the  same  protec- 
tion which  a  cab  gives  to  the  locomotive  engineer. 

We  will  answer  as  well  as  we  may  the  second  ques- 
tion, Upon  how  gentle  a  decline  may  we  hope  to  see  an 
aerial  machine  maintain  its  initial  velocity?  When  a 
railway  car  is  at  rest  upon  a  smooth  steel  track  having 
a  down  grade  of  one  and  twenty-three  one-hundredths 
feet  in  every  one  hundred  feet,  it  will  remain  at  rest  if 
undisturbed;  but  let  it  be  once  started  downward  by 
ever  so  slight  an  impulse  and  it  will  run  down  the  track, 
gaining  velocity  to  the  end  of  the  grade.  It  encounters 
the  head  resistance  of  the  air  and  the  friction  of  the 
track,  but  an  aerial  machine  would  encounter  only  air- 
resistance  ;  is  it  not,  therefore,  reasonable  to  suppose  that 
a  dirigible  aeroplane  would  in  a  calm,  maintain  its  initial 
velocity  while  running  upon  a  down  grade  of  air  of  one 
foot  in  every  one  hundred  feet?  If  so,  an  altitude  of 
ten  or  twelve  hundred  feet  would  send  a  soaring  ma- 
chine eighteen  or  twenty  miles,  and  greater  altitudes 
would  give  longer  flights,  if,  as  may  be  supposed,  the 
rarefaction  of  the  air  can  be  offset  by  an  increase  of 
velocity.  These  are  surmises,  but  the  way  to  learn  is 
to  experiment  with  soaring  machines. 

It  is  above  all  things  important  that  a  soaring  machine 
should,  when  desired,  automatically  keep  itself  in  a 
horizontal  or  slightly  descending  course.  I  have  this 


14  THE    PROBLEM    OF    MANFLIGHT. 

winter  begun  a  series  of  experiments  with  soaring 
machines,  and  when  these  are  finished  the  full  details 
will  be  reported. 

In  November,  1893,  I  launched  several  of  these 
machines  from  the  balcony  of  the  tower  of  Boston 
Light,  and  more  recently  I  have  experimented  from  the 
top  of  the  cliffs  at  Manomet.  The  former  place  is  an 
ideal  one  for  the  purpose  of  experiment,  being  as  it  is, 
one  hundred  and  eleven  feet  above  the  sea  with  a  straight 
drop  of  seventy  or  eighty  feet.  Unfortunately,  a  gale  of 
wind  was  blowing  when  I  visited  the  light,  and  two  out 
of  the  three  machines  were  total  failures,  being  badly 
bent  by  the  wind  before  they  were  launched.  The  third 
machine  righted  itself  before  reaching  the  ground,  but 
the  pendulum,  which  will  presently  be  described,  was 
too  light  to  do  efficient  work. 

The  experiments  from  the  cliffs  at  Manomet  were  even 
less  successful,  owing  to  the  fact  that  the  descent  is  not 
sheer.  All  of  the  machines  failed  to  gain  sufficient 
velocity  to  clear  the  cliff. 

Those  who  wish  to  experiment  with  machines  weigh- 
ing only  a  few  pounds  will  probably  find  that  a  height 
of  seventy  or  eighty  feet  will  be  sufficient  if  the  position 
gives  a  straight  drop.  When  it  comes  to  experimenting 
with  a  soaring  machine  as  large  as  LilienthaPs  and  carry- 
ing a  weight  representing  that  of  a  man,  the  summit  of 
Mt.  Willard,  near  the  Crawford  House,  N.H.,  will  be 
found  an  excellent  place. 

To  any  one  who  desires  to  take  up  this  most  fascinat- 
ing study,  Figs.  3  and  4  will  give  a  general  idea  as  to  the 
construction  of  his  first  instrument  for  making  experi- 
ments. A  represents  a  backbone  five-eighths  of  an 
inch  square  and  four  feet  long,  made  of  pine  wood; 
B,  the  main  aeroplane,  eight  inches  wide  and  three  feet 


THE    PROBLEM    OF    MANFLIGHT.  17 

long.  This  should  be  made  of  light  tin  plate,  and  bent 
in  the  middle  so  as  to  form  a  flattened  V;  the  angle 
should  be  about  one  hundred  and  seventy  degrees. 
C  represents  a  steering  aeroplane  six  inches  by  twenty- 
four  inches,  pivoted  at  cc,  also  made  of  light  tin  plate; 
D,  a  vertical  aeroplane  four  inches  by  twenty  inches, 
rigidly  fixed  in  the  wooden  backbone;  E,  a  rod  of 
steel  wire,  eighteen  or  twenty  inches  long,  and  carrying 
an  adjustable  leaden  weight  of  three  ounces;  K,  a  rod 
two  and  one-half  inches  long,  soldered  in  the  centre  of 
and  vertical  to  the  plane  C,  with  a  pivot  at  the  upper 
end  with  which  the  rod  MM  is  connected.  This  rod 
should  have  five  or  six  pivot-holes  at  its  forward  end  N, 
so  that  its  working  length  may  be  varied  for  different 
experiments;  J,  a  rod  pivoted  at  G,  free  to  swing  fore 
and  aft;  N,  a  pivot  where  the  rod  MM  joins  the  rod  J; 
F,  a  leaden  weight  adjustable  higher  or  lower  upon  the 
rod  J;  its  proper  weight  is  x,  an  unknown  quantity. 
Upon  ascertaining  by  repeated  experiment  the  right 
'weight  for  F,  the  right  position  for  the  adjustable 
weight  E,  and  the  right  length  for  the  rod  MM,  the  reach- 
ing of  the  maximum  efficiency  of  a  system  of  aeroplanes 
largely  depends.  I  think  that  this  sets  forth  with  clear- 
ness the  problem  as  it  stands  to-day.  When  it  is  fully 
solved  —  and  it  certainly  seems  solvable  —  right  and  left 
steering  will  be  a  less  difficult  matter,  and  alighting 
will  be  accomplished  by  killing  the  momentum  when 
near  the  ground  by  an  abrupt  upward  slant  of  the  main 
aeroplanes;  but  this  is  an  anticipation  and  a  digression. 
Now  to  return  to  the  instrument  we  are  considering: 

o 

this  soaring  machine  is  intended  to  gain  velocity  by  a 
swoop,  and  then  automatically  steer  itself  into  a  hori- 
zontal or  very  slightly  descending  course,  as  indicated 
by  B  and  C  in  Fig.  2.  It  depends  upon  the  principle 


1 8  THE    PROBLEM    OF    MANFLIGHT. 

that  the  pendulum  rod  always  seeks  the  perpendicular; 
for  instance,  when  the  machine  is  launched  pointing 
steeply  downward,  the  positions  of  the  pendulum  and 
aeroplanes  are  as  shown  in  Fig.  5 ;  therefore  the  steer- 
ing aeroplane  C  will,  as  soon  as  velocity  is  gained,  lay 


F.6  7 


a  strong  hold  upon  the  wind  of  flight,  and  have  a  ten- 
dency to  bring  the  machine  into  a  horizontal  course. 
Now,  if  the  length  of  the  rod  MM  is  made  correct  by 
adjustment  at  the  pivot-holes  near  N,  when  the  desired 
course,  a  very  gentle  decline,  is  reached,  both  aero- 
planes will  be  approximately  horizontal,  as  shown  in 
Fig.  6.  If,  however,  the  machine  deviates  either 
upward  or  downward  from  its  intended  course,  the 
weight  at  the  end  of  the  pendulum  causes  the  steering 
aeroplane  to  correct  the  error.  Fig.  7  shows  the 
effect  of  a  slight  upward  deviation. 

H  represents  a  long  and  very  slender  air-recepta- 
cle made  of  thin  rubber  and  inflated;  this  should  be 
pointed  at  both  ends.  It  may  be  used  to  keep  the 
machine  afloat  when  experiments  are  made  near  the 
water.  I  have  not  yet  used  this,  but  have  allowed  my 
machines  to  go  to  pieces.  The  design  here  given  calls 
for  aeroplanes  as  being  more  easily  made  than  aero- 
curves  modelled  after  the  wings  of  birds,  but  in  all 
probability  the  latter  will  eventually  displace  the  former. 

We  are  brought  now,  after  this  consideration  of  the 
greatest  mechanical  problem  of  the  age,  to  ask,  What 


THE    PROBLEM    OF    MANFLIGHT.  19 

shall  be  done  to  bring  to  our  own  century  the  credit 
and  honor  of  reaching  the  solution? 

The  answer  is,  encourage  experiments  with  soaring 
machines.  Have  regattas  and  large  prizes.  Appeal  to 
the  people's  love  of  sport,  and  show  what  possibilities 
of  recreation  have  been  suggested  by  the  experiments 
of  Otto  Lilienthal.  Tobogganing  on  ice  we  can  have 
only  a  few  weeks  in  the  year:  tobogganing  on  air  is 
possible  at  all  seasons.  When  we  have  made  our  aero- 
planes or  aerocurves  automatic  in  their  steering  action, 
flights  like  Lilienthal's  will  be,  to  say  the  least,  no 
more  dangerous  than  football  and  quite  as  interesting. 

In  order  to  encourage  the  designing  and  construction 
of  soaring  machines,  I  suggest  that  a  sum  of  money  be 
raised  to  be  offered  as  a  prize  to  the  constructor  of  the 
most  successful  soaring-machine,  the  award  to  be  made 
after  a  public  trial  of  the  same,  to  take  place  early  in 
September  of  the  present  year  (1894). 

I  will  subscribe  one  hundred  dollars  if  others  will 
subscribe,  in  any  sums  they  choose,  nine  hundred  dol- 
lars more,  to  make  a  purse  of  one  thousand  dollars, 
provided  that  the  publisher  of  some  journal  oi  wide 
influence  will  be  custodian  of  the  fund. 

One  or  two  more  thoughts  in  conclusion.  We  have 
seen  how  the  soaring  bird  tacks,  first  up,  then  down, 
then  up  again,  and  then  down  again.  That  conveys  the 
idea  of  the  perfection  of  rapid  transit  for  passengers 
and  freight.  With  the  captive  balloon  we  can  tack  up, 
with  the  soaring  machine  we  can  tack  down.  Short 
tacks  up,  long  tacks  down;  there  is  no  calm  for  the 
aeroplane;  give  it  altitude  and  it  can  seize  from  the 
calm  the  wind  of  flight. 

Imagine  a  bowling  alley  four  hundred  feet  long,  per- 
fectly level,  with  an  athlete  at  one  end  and  a  boy  at  the 

'  • 


20  THE    PROBLEM    OF    MANFLIGHT. 

other.  Let  the  chute  which  returns  the  balls  have  a 
drop  of  fifteen  inches  in  every,  one  hundred  feet;  im- 
agine the  game  to  be  one  of  rapid  transit  instead  of  ten- 
pins. It  is  P  competition  between  the  two  ends  of  the 
ajley  to  see  which  end  can  make  the  most  of  what 
energy  it  has.  Let  the  athlete  exert  all  his  strength 
to  propel  the  spheres ;  see  them  arrive  at  the  end  of  the 
alley  after  their  journey  of  four  hundred  feet,  with 
sluggish  speed;  the  boy  lifts  them  to  a  height  of  five 
feet  to  the  chute,  gives  them  a  gentle  push,  and  they  are 
returned  to  the  athlete's  end,  arriving,  not  as  sluggards, 
but  as  filled  with  energy.  A  short  tack  up  and  a  long 
tack  down  is  what  does  it. 

There  you  have  the  old  and  the  new  methods  of  transit 
represented.  The  athlete  represents  the  steam  loco- 
motive which,  with  all  its  polish  and  glitter,  wastes 
energy.  The  boy  represents  the  balloon,  the  lifter, 
which  stores  energy  in  matter  by  giving  it  altitude. 
The  chute  represents  the  free  highway  which  through 
all  the  centuries  men  have  supposed  to  be  lacking. 

Aerial  transit  will  be  accomplished  because  the  air 
is  a  solid  if  you  hit  it  hard  enough. 

James  Means. 


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